Simplified design of composite beams with large web openings to Eurocode 4

Abstract

The design of composite beams with large rectangular or circular openings is an important structural and practical problem which is caused by the need to pass service ducts through the structural zone of floor systems. Careful sizing and positioning of these openings in the beam webs can minimise their adverse effects on the shear and the bending resistances of composite beams. A design method [1][Lawson, RM. Design for openings in the webs of composite beams. The Steel Construction Institute/CIRIA joint publication SCI-P068, 1987.] for composite beams with large web openings was first formulated in accordance with BS5950 and calibrated against full-scale tests in 1992 [2][Lawson RM, Chung KF, Price AM. Tests on composite beams with large web openings to justify existing design methods. Struct Eng 1992:70(1).]. With the release of the draft Eurocode 4 in 1994 [3][ENV 1994-1-1: Eurocode 4: design of composite steel and concrete structures. BSI, 1994.], this paper re-presents the design method in the format of application rules to Eurocode 4 for detailed design of composite beams with large web openings. Moreover, the designer needs advice at the scheme design stage, and this paper also presents general information on sizing of openings as a function of the utilisation of the shear and the bending resistances of composite beams. Furthermore, the effect of these openings on deflections is estimated by a simple factor which is dependent on the size and the location of the openings. Typical design tables for composite beams with large rectangular openings are presented. Design rules for other forms of construction such as circular openings and notched beams are also presented with general detailing rules to assist designers.